114 research outputs found
Corrigendum: “A Correlation for Interfacial Area Concentration in High Void Fraction Flows in Large Diameter Channels” ([Chem. Eng. Sci.131 (2015) 172–186] (2015) 131 (172–186), (S0009250915002547), (10.1016/j.ces.2015.04.004))
There is a Typographical Mistake in Eq. (21), Used in the Derivation of the Final Model, Which Should Read [Fourmula Presented] This Typographical Mistake is Also Present in Eq. (22b), Which is Necessary for Implementation of the Final Model, Which Should Rea
Experiments performed with bubbly flow in vertical pipes at different flow conditions covering the transition region: Simulation by coupling Eulerian, Lagrangian and 3D random walks models
[EN] Two phase flow experiments with different superficial velocities of gas and water were performed in a vertical upward isothermal cocurrent air-water flow column with conditions ranging from bubbly flow, with very low void fraction, to transition flow with some cap and slug bubbles and void fractions around 25%. The superficial velocities of the liquid and the gas phases were varied from 0.5 to 3 m/s and from 0 to 0.6 m/s, respectively. Also to check the effect of changing the surface tension on the previous experiments small amounts of 1-butanol were added to the water. These amounts range from 9 to 75 ppm and change the surface tension. This study is interesting because in real cases the surface tension of the water diminishes with temperature, and with this kind of experiments we can study indirectly the effect of changing the temperature on the void fraction distribution. The following axial and radial distributions were measured in all these experiments: void fraction, interfacial area concentration, interfacial velocity, Sauter mean diameter and turbulence intensity. The range of values of the gas superficial velocities in these experiments covered the range from bubbly flow to the transition to cap/slug flow. Also with transition flow conditions we distinguish two groups of bubbles in the experiments, the small spherical bubbles and the cap/slug bubbles. Special interest was devoted to the transition region from bubbly to cap/slug flow; the goal was to understand the physical phenomena that take place during this transition A set of numerical simulations of some of these experiments for bubbly flow conditions has been performed by coupling a Lagrangian code, that tracks the three dimensional motion of the individual bubbles in cylindrical coordinates inside the field of the carrier liquid, to an Eulerian model that computes the magnitudes of continuous phase and to a 3D random walk model that takes on account the fluctuation in the velocity field of the carrier fluid that are seen by the bubbles due to turbulence fluctuations. Also we have included in the model the deformation that suffers the bubble when it touches the wall and it is compressed by the forces that pushes it toward the wall, provoking that the bubble rebound like a ball.The authors of this paper are indebted to the National Plan of I+D by the support of the coordinated projects REMOD-ERN ENE2010-21368-C02-01/CON and ENE2010-21368-C02-02/CON to perform the experiments.Muñoz-Cobo, JL.; Chiva, S.; Ali Abdelaziz Essa, M.; Mendez, S. (2012). Experiments performed with bubbly flow in vertical pipes at different flow conditions covering the transition region: Simulation by coupling Eulerian, Lagrangian and 3D random walks models. Archives of Thermodynamics. 33(1):3-39. https://doi.org/10.2478/v10173-012-0001-4S33933
MOA-2020-BLG-135Lb: A New Neptune-class Planet for the Extended MOA-II Exoplanet Microlens Statistical Analysis
We report the light-curve analysis for the event MOA-2020-BLG-135, which
leads to the discovery of a new Neptune-class planet, MOA-2020-BLG-135Lb. With
a derived mass ratio of and separation
, the planet lies exactly at the break and likely peak of the
exoplanet mass-ratio function derived by the MOA collaboration (Suzuki et al.
2016). We estimate the properties of the lens system based on a Galactic model
and considering two different Bayesian priors: one assuming that all stars have
an equal planet-hosting probability and the other that planets are more likely
to orbit more massive stars. With a uniform host mass prior, we predict that
the lens system is likely to be a planet of mass
and a host star of mass
, located at a distance
. With a prior that holds that planet
occurrence scales in proportion to the host star mass, the estimated lens
system properties are ,
, and . This planet qualifies for inclusion in the extended MOA-II
exoplanet microlens sample.Comment: 22 pages, 6 figures, 4 tables, submitted to the AAS Journal
KMT-2021-BLG-1547Lb: Giant microlensing planet detected through a signal deformed by source binarity
We investigate the previous microlensing data collected by the KMTNet survey
in search of anomalous events for which no precise interpretations of the
anomalies have been suggested. From this investigation, we find that the
anomaly in the lensing light curve of the event KMT-2021-BLG-1547 is
approximately described by a binary-lens (2L1S) model with a lens possessing a
giant planet, but the model leaves unexplained residuals. We investigate the
origin of the residuals by testing more sophisticated models that include
either an extra lens component (3L1S model) or an extra source star (2L2S
model) to the 2L1S configuration of the lens system. From these analyses, we
find that the residuals from the 2L1S model originate from the existence of a
faint companion to the source. The 2L2S solution substantially reduces the
residuals and improves the model fit by with respect to the
2L1S solution. The 3L1S solution also improves the fit, but its fit is worse
than that of the 2L2S solution by . According to the 2L2S
solution, the lens of the event is a planetary system with planet and host
masses lying at a distance \D_{\rm L}
=5.07^{+0.98}_{-1.50}~kpc, and the source is a binary composed of a subgiant
primary of a late G or an early K spectral type and a main-sequence companion
of a K spectral type. The event demonstrates the need of sophisticated modeling
for unexplained anomalies for the construction of a complete microlensing
planet sample.Comment: 9 pages, 4 tables, 7 figure
KMT-2022-BLG-0440Lb: A New Microlensing Planet with the Central-Resonant Caustic Degeneracy Broken
We present the observations and analysis of a high-magnification microlensing
planetary event, KMT-2022-BLG-0440, for which the weak and short-lived
planetary signal was covered by both the KMTNet survey and follow-up
observations. The binary-lens models with a central caustic provide the best
fits, with a planet/host mass ratio, -- at
. The binary-lens models with a resonant caustic and a brown-dwarf
mass ratio are both excluded by . The binary-source model
can fit the anomaly well but is rejected by the ``color argument'' on the
second source. From Bayesian analyses, it is estimated that the host star is
likely a K or M dwarf located in the Galactic disk, the planet probably has a
Neptune-mass, and the projected planet-host separation is
or au, subject to the close/wide degeneracy. This is the
third planet from a high-magnification planetary signal (). Together with another such planet, KMT-2021-BLG-0171Lb, the
ongoing follow-up program for the KMTNet high-magnification events has
demonstrated its ability in detecting high-magnification planetary signals for
planets, which are challenging for the current microlensing
surveys.Comment: MNRAS accepte
Digitalization or flexibilization? The changing role of technology in the political economy of Japan
We are increasingly surrounded by talk of digitalization. Yet, we remain unsure about what impact this digitalization will have upon socio-economic institutions, how the introduction of this digitalization will be contested, the likely role of the state in managing the adoption of digital technology, and the likely consequences for the broader political economy if and when it is introduced. This article examines the process of digitalization as it has unfolded in the service sector in Japan. Based on qualitative interviews with managers in the hospitality industry and union officials, the paper depicts a process that contrasts starkly with the more optimistic view adopted by some commentators, according to which digitalization has the potential to improve working conditions and contribute to a more stable form of growth. Instead, the paper draws on Regulation Theory to argue that the introduction of digitalization is part of a wider process of neoliberalization. As such, digitalization has contributed to deskilling, the fragmentation of work tasks, a digital divide, the intensification of work, and higher levels of workplace surveillance. This represents a further dismantling of the social compromise that underpinned Japan’s earlier period of economic growth
Corrigendum to A Correlation for Interfacial Area Concentration in High Void Fraction Flows in Large Diameter Channels [Chem. Eng. Sci. 131 (2015) 172-186]
This corrigendum corrects some errors in the derivations of the equations presented in the original article. All information in this corrigendum supersedes any previous corrigenda.
There were two significant errors in the original derivation.
(1) Typographic errors in Eqs. (17) and (24) carried through to Eqs. (22) and (26), and from there to the values of the empirical constants and the model predictions.
(2) The incorrect value was used for the constant CTI.
These errors required updating the equations and constants from the original manuscript. As a result the empirical constants must be changed and Figs. 9, 10, 11, and 17 are updated
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